Osteoclast Morphology

This was a 32 year old patient whose bone marrow aspiration was done for a suspected diagnosis of a leukaemia. The aspirate yielded a scanty amount of pauciparticulate marrow. Blasts were seen. What was remarkable was the presence of many osteoclasts along a clot on the smear. One of the osteoclasts is seen here in low power. Note the size relative to the erythrocyte.	The same osteoclast shown in the previous image unser 100X.	Another osteoclast in the same smear. The multiple nuclei. Each nucleus is 1.5-2X adjoining erythrocytes. This gives an idea of the size of the cells.	A megakaryocytic though a large cell like an osteoclast normally has a single multi-lobed nucleus

Osteoclast are multinucleate bone resorbing cells derived from the haemopoietic stem cell. An osteoclast is about 30-100μ in size and has multiple discrete oval nuclei. They have azurophilic granules. The megakaryocyte though a large cell, unlike an osteoclast, normally has a single multi-lobed nucleus. Osteoclasts are truly multinucleate. The azurophilic granules of osteoclasts are coarser.